“Robert Jeffress says, ‘You can’t be saved by being a Jew,’ and ‘Mormonism is a heresy from the pit of hell,’” Romney wrote in a tweet Sunday night. “He’s said the same about Islam. Such a religious bigot should not be giving the prayer that opens the United States Embassy in Jerusalem.”

Jeffress bases his beliefs and his general opposition to a two-state solution to the conflict between Israel and the Palestinians on his strict interpretation of the Bible.

“The Bible says this land belongs to the Jewish people — period,” he told NBC News in a separate interview in February. "God has pronounced judgment after judgment in the Old Testament to those who would ‘divide the land,’ end quote, and hand it over to non-Jews.”

"If you sincerely follow the tenets of Islam, then you will end up in hell when you die."

The Rev. Robert Jeffress

While a staunch ally of the government of Israeli Prime Minister Benjamin Netanyahu, Jeffress has been criticized for preaching that all non-Christians, including people who are Jewish, will not go to heaven.

“The truth everyone headed to hell has rejected is that Jesus Christ is the only means by which a person may be saved,” Jeffress said in a Feb. 6, 2017, video posted on his church's website. “Jesus could not have been more clear [when] he said, ‘I am the way, the truth and the life. No one comes to the Father but through me.'”

Jeffress has also been open about his beliefs on Islam.

"Is Islam just another way to worship God? Let me say this without any hesitation: Islam is a false religion that is based on a false book that was written by a false prophet," he said on Oct. 9, according to his church's website. "If you sincerely follow the tenets of Islam, then you will end up in hell when you die."

Jeffress added, "By upholding God’s pattern for sexuality — a man and a woman in a marriage relationship — Jesus automatically condemned any deviation from that pattern."

Jeffress isn’t the only conservative evangelical leader to be on hand for Monday's embassy ceremony, which included around 800 guests. The Rev. John Hagee, the founder of influential evangelical Christians United for Israel and a pastor from San Antonio, delivered a closing blessing at the ceremony.

American evangelicals surged onto the political scene in 1980 by helping to elect President Ronald Reagan. In 2016, around 80 percent of white evangelicals voted for Trump. As evangelicals grew more prominent domestically, their ties to the Israeli political establishment strengthened.

Hagee has explicitly linked the establishment of the state of Israel to biblical prophecy and the second coming of Jesus.

“The rebirth of Israel as a nation was an unmistakable milestone on the prophetic timeline leading to the return of Christ,” he wrote in his book, “In Defense of Israel.”

Trump and Vice President Mike Pence have been embraced by Christian Zionists who believe the establishment of the state of Israel is proof of God keeping his promises and a step toward the second coming of Christ.

Many European nations who oppose Trump's decision to move the embassy are expected to skip related events on Monday.